Mendes, Joao, and Rodrigo Ventura. “Assisted Teleoperation of Quadcopters Using Obstacle Avoidance”. Journal of Automation, Mobile Robotics and Intelligent Systems, vol. 7, no. 1, Aug. 2013, pp. 54-58, https://jamris.d.tomp.pl/index.php/JAMRIS/article/view/256.